Pseudo Elevation of TSH and ACTH Caused by Heterophilic Antibodies: a Case Report and Literature Review

BACKGROUND

TSH and ACTH are crucial hormones for diagnosing thyroid and adrenal diseases, and incorrect test reports can cause significant harm to patients.

METHODS

The TSH and ACTH levels on the testing system of our laboratory were measured using "sandwich" assays. The patient had heterophilic antibodies in their body, causing a false increase in TSH and ACTH levels.

RESULTS

TSH on the Abbott platform was 59.7 μIU/mL and on the Roche platform it was 4.33 μIU/mL. After pretreatment with HBR it was 3.95 μIU/mL; ACTH on the SIEMENS platform was 263.5 pg/mL, on the Abbott platform it was 47.6 pg/mL. After pretreatment with HBR it was 36.5 pg/mL.

CONCLUSIONS

The patient's serum contains heterophilic antibodies, which interfere with the TSH and ACTH tested by this method.

A Pseudo Elevation of CEA Caused by Epidemic Hemorrhagic Fever

BACKGROUND

Heterophilic antibodies (HA) are one of the main substances that interfere with immunology, especially chemiluminescence immunoassay. Non-specific binding, labeling antibodies, bridging to capture antibodies, or labeling antigens can interfere with the detection process, leading to serious discrepancies between the measured results and clinical manifestations, and even delaying clinical diagnosis and treatment.

METHODS

This paper is a case of epidemic hemorrhagic fever causing pseudo CEA elevation caused by heterophagy induced antibodies in the body.

RESULTS

The patient's CEA detected on the ABBOTT detection platform was 51.1 ng/mL, and on the ROCHE detection platforms it was 4.66 ng/mL, and treated by PEG precipitation it was 45.2 ng/mL, after diluting the sample the CEA was 50.2 ng/mL, meanwhile the patient's platelets were 96 x 109/L and serum creatinine was 188.4 μmol/L, epidemic hemorrhagic fever IgM antibody was positive.

CONCLUSIONS

When the test results do not match clinical symptoms, further confirmation is required through additional testing. Patients who use mouse monoclonal antibody preparations for diagnosis or treatment may have human anti-mouse antibodies in their serum, and the test results may falsely increase or decrease.

Anti-pig antibodies in swine veterinarian serum: Implications for clinical xenotransplantation

Recent clinical xenotransplantation and human decedent studies demonstrate that clinical hyperacute rejection of genetically engineered porcine organs can be reliably avoided but that antibody mediated rejection (AMR) continues to limit graft survival. We previously identified porcine glycans and proteins which are immunogenic after cardiac xenotransplantation in non-human primates, but the clinical immune response to antigens present in glycan depleted triple knockout (TKO) donor pigs is poorly understood. In this study we use fluorescence barcoded human embryonic kidney cells (HEK) and HEK cell lines expressing porcine glycans (Gal and SDa) or proteins (tetraspanin-29 [CD9], membrane cofactor protein [CD46], protectin, membrane attack complex inhibition factor [CD59], endothelial cell protein C receptor, and Annexin A2) to screen antibody reactivity in human serum from 160 swine veterinarians, a serum source with potential occupational immune challenge from porcine tissues and pathogens. High levels of anti-Gal IgM were present in all samples and lower levels of anti-SDa IgM were present in 41% of samples. IgM binding to porcine proteins, primarily CD9 and CD46, previously identified as immunogenic in pig to non-human primate cardiac xenograft recipients, was detected in 28 of the 160 swine veterinarian samples. These results suggest that barcoded HEK cell lines expressing porcine protein antigens can be useful for screening human patient serum. A comprehensive analysis of sera from clinical xenotransplant recipients to define a panel of commonly immunogenic porcine antigens will likely be necessary to establish an array of porcine non-Gal antigens for effective monitoring of patient immune responses and allow earlier therapies to reverse AMR.

Human chorionic gonadotropin suspected heterophile interference investigations in immunoassays: a recommended approach

Background Heterophile antibody (HAb) interferences in immunoassays can cause falsely elevated hCG concentrations leading to incorrect diagnosis and treatments options. When results are not consistent with the clinical findings, hCG HAb interference investigation may be requested by the physician. A retrospective evaluation of the frequency of HAb interference was performed among cases of physician-requested investigations and the effectiveness of commercially available blocking reagents to detect HAb interference in two immunoassay systems was evaluated. Methods One hundred and thirteen physician requests for hCG HAb investigation from 2008 to 2017 were reviewed. The primary method used to measure hCG was the Beckman Coulter Access Total βhCG (2008-2010) and the Roche Elecsys HCG+β (2014-2017). HAb investigation included measurement by two immunoassays before and after treatment of samples with heterophile blocking reagents and serial dilution studies. Results Five cases of HAb and HAb-like interference were identified. The interference frequency was 6.7% for the Beckman assay and 2.9% for the Roche assay. The presence of HAb was detected using heterophile blocking reagents and an alternative method in three cases. The other two cases were detected due to discrepant results with an alternative method and non-linear serial dilutions (HAb-like). Conclusions HAb interference was observed in the Beckman and the Roche assays. The heterophile blocking reagents failed to detect 40% of interference cases. Blocking reagents should not solely be used for these investigations. Multiple strategies including the use of serial dilutions and using an alternative platform are critical when troubleshooting interferences in hCG immunoassays.

Relapse of Nephrotic Syndrome after Adrenocorticotropic Hormone-Induced Remission: Implications of Adrenocorticotropic Hormone Antibodies

BACKGROUND

Prolonged use of corticosteroids continues to be the mainstay in the management of most proteinuric glomerulopathies, but is limited by extensive side effects. Alternative medications such as adrenocorticotropic hormone (ACTH) have been recently used to treat refractory glomerulopathies and have shown superior outcomes when compared with steroids. However, the clinical responsiveness to ACTH therapy varies considerably with a number of patients exhibiting de novo or acquired resistance. The underlying mechanism remains unknown.

METHODS

A patient with steroid-dependent focal segmental glomerulosclerosis (FSGS) developed severe steroid side effects impacting quality of life and was converted to repository porcine ACTH therapy. Immediate response in the form of remission of nephrotic syndrome was noted followed by relapse in 10 weeks. Suspecting the role of some ACTH-antagonizing factors, the patient's serum was examined.

RESULTS

Immunoblot-based antibody assay revealed high titers of de novo IgG antibodies in the patient's serum that were reactive to the porcine corticotropin with negligible cross-reactivity to human corticotropin. In vitro, in cultured B16 melanoma cells that express abundant melanocortin receptors, addition of the patient's serum substantially abrogated the porcine corticotropin triggered signaling activity of the melanocortinergic pathway, marked by phosphorylation of glycogen synthase kinase 3β, thus suggesting a mitigating effect on the biological functionality of porcine corticotropin.

CONCLUSION

ACTH is a useful alternative therapeutic modality for refractory proteinuric glomerulopathies like FSGS. However, as quintessential therapeutic biologics, natural ACTH, regardless of purity and origin, is inevitably antigenic and may cause the formation of neutralizing antibodies in some sensitive patients, followed by resistance to ACTH therapy. It is imperative to develop ACTH analogues with less immunogenicity for improving its responsiveness in patients with glomerular diseases.

Studying Xenograft Rejection of Bioprosthetic Heart Valves

Millions of patients with valvular heart disease have benefitted from heart valve replacement since the procedure was first introduced in the 1960s; however, there are still many patients who get early structural valve deterioration (SVD) of their bioprosthetic heart valves (BHV). BHV are porcine, bovine, or equine tissues that have been glutaraldehyde fixed to preserve the tissue and presumably make the tissue immunologically inert. These glutaraldehyde-fixed BHV with anti-calcification treatments last long periods of time in older adults but develop early SVD in younger patients. The consensus at present is that the early SVD in younger patients is due to more "wear and tear" of the valves and higher calcium turnover in younger patients. However, as younger patients likely have a more robust immune system than older adults, there is a new hypothesis that BHV xenografts may undergo xenograft rejection, and this may contribute to the early SVD seen in younger patients.At present, the technology to noninvasively study in vivo whether an implanted BHV in a human patient is undergoing rejection is not available. Thus, a small animal discordant xenotransplant model in young rodents (to match the young patient getting a pig/bovine/equine BHV) was developed to study whether the hypothesis that glutaraldehyde-fixed BHV undergo xenograft rejection had any merit. In this chapter, we describe our model and its merits and the results of our investigations. Our work provides clear evidence of xenograft rejection in glutaraldehyde-fixed tissue, and our small animal model offers an opportunity to study this process in detail.

PTH Immunoassay Interference Due to Human Anti-Mouse Antibodies in a Subject With Obesity With Normal Parathyroid Function

CONTEXT

Immunoassay interference has been most often found with prolactin measurement. However, only few data exist on immunoassay interference for other hormones.

CASE DESCRIPTION

A 36-year-old woman with obesity (body mass index, 31 kg/m2) had regularly attended our endocrine unit for type 2 diabetes therapy. When she was included as a control subject in a study for obesity management, detailed laboratory testing was performed, including PTH. In the absence of clinical symptoms, she presented with normal calcium, phosphate, and vitamin D levels. However, the PTH levels were >5000 ng/L. These results were obtained using the Roche Elecsys electrochemiluminescence assay. Repeated measurements with this assay (mouse antibody) led to the same findings. However, using an Euroimmun assay (goat antibody), the exact PTH values were measured at 18.0 ng/L. After pretreatment with a heterophilic antibody blocking reagent, the results of the Roche assay had decreased to a normal level. This phenomenon was explained by the detection of human anti-mouse antibodies in the proband's serum.

CONCLUSIONS

In cases of prolactin immunoassay interference, endogenous antibodies will bind to the hormone in vivo, resulting in complexes of a high molecular weight that are less efficiently cleared by the kidneys and, thus, accumulate in the blood. In contrast, the PTH values >5000 ng/L detected in our subject most likely had resulted from the specific interference of the human anti-mouse antibodies present in the proband's serum with the assay antibody, resulting in artificial stimulation of the Roche assay detection system ex vivo.

The complex functioning of the complement system in xenotransplantation

The role of complement in xenotransplantation is well-known and is a topic that has been reviewed previously. However, our understanding of the immense complexity of its interaction with other constituents of the innate immune response and of the coagulation, adaptive immune, and inflammatory responses to a xenograft is steadily increasing. In addition, the complement system plays a function in metabolism and homeostasis. New reviews at intervals are therefore clearly warranted. The pathways of complement activation, the function of the complement system, and the interaction between complement and coagulation, inflammation, and the adaptive immune system in relation to xenotransplantation are reviewed. Through several different mechanisms, complement activation is a major factor in contributing to xenograft failure. In the organ-source pig, the detrimental influence of the complement system is seen during organ harvest and preservation, for example, in ischemia-reperfusion injury. In the recipient, the effect of complement can be seen through its interaction with the immune, coagulation, and inflammatory responses. Genetic-engineering and other therapeutic methods by which the xenograft can be protected from the effects of complement activation are discussed. The review provides an updated source of reference to this increasingly complex subject.

The effects of early postoperative immunization with xenogeneic embryo proteins on Lewis lung carcinoma model

AIM

To investigate the effect of chicken embryo proteins (CEP) as a prototype of xenogeneic vaccine on immune reactions in mice immunized after Lewis lung carcinoma (LLC) surgical removal.

MATERIALS AND METHODS

C57Bl male mice were immunized on days 1, 8, and 15 after surgical removal of LLC. The immune response was assessed on days 7, 14, 21 and 28 after tumor resection. Cytotoxic activity of natural killer cells (NK) and cytotoxic T-lymphocytes as well as antibody dependent cellular cytotoxicity was estimated in MTT-assay; specific antibodies were detected in ELISA; lymphocyte proliferation was tested in reaction of in vitro blast transformation.

RESULTS

None of the immunized mice developed LLC metastases. Immunization with CEP seems to prevent the potential decrease in NK cell cytotoxic activity and spontaneous blast transformation activity of lymphocytes following the surgically induced stress. Further research on improving immunization schedule and elucidating the mechanisms of NK modulation with CEP is needed.

Anti-C1 domain antibodies that accelerate factor VIII clearance contribute to antibody pathogenicity in a murine hemophilia A model

Essentials Inhibitor formation remains a challenging complication of hemophilia A care. The Bethesda assay is the primary method used for determining bleeding risk and management. Antibodies that block factor VIII binding to von Willebrand factor can increase FVIII clearance. Antibodies that increase clearance contribute to antibody pathogenicity.

SUMMARY

Background The development of neutralizing anti-factor VIII (FVIII) antibodies remains a challenging complication of modern hemophilia A care. In vitro assays are the primary method used for quantifying inhibitor titers, predicting bleeding risk, and determining bleeding management. However, other mechanisms of inhibition are not accounted for in these assays, which may result in discrepancies between the inhibitor titer and clinical bleeding symptoms. Objectives To evaluate FVIII clearance in vivo as a potential mechanism for antibody pathogenicity and to determine whether increased FVIII dosing regimens correct the associated bleeding phenotype. Methods FVIII-/- or FVIII-/- /von Willebrand factor (VWF)-/- mice were infused with anti-FVIII mAbs directed against the FVIII C1, C2 or A2 domains, followed by infusion of FVIII. Blood loss via the tail snip bleeding model, FVIII activity and FVIII antigen levels were subsequently measured. Results Pathogenic anti-C1 mAbs that compete with VWF for FVIII binding increased the clearance of FVIII-mAb complexes in FVIII-/- mice but not in FVIII-/- /VWF-/- mice. Additionally, pathogenic anti-C2 mAbs that inhibit FVIII binding to VWF increased FVIII clearance in FVIII-/- mice. Anti-C1, anti-C2 and anti-A2 mAbs that do not inhibit VWF binding did not accelerate FVIII clearance. Infusion of increased doses of FVIII in the presence of anti-C1 mAbs partially corrected blood loss in FVIII-/- mice. Conclusions A subset of antibodies that inhibit VWF binding to FVIII increase the clearance of FVIII-mAb complexes, which contributes to antibody pathogenicity. This may explain differences in the bleeding phenotype observed despite factor replacement in some patients with hemophilia A and low-titer inhibitors.

EORTC Receptor and Biomarker Study Group Report: A Sandwich Enzyme-Linked Immunosorbent Assay for Vascular Endothelial Growth Factor in Blood and Tumor Tissue Extracts

A four-antibody sandwich enzyme-linked immunosorbent assay (ELISA) for vascular endothelial growth factor (VEGF) for application in blood (serum and plasma) and tumor tissue extracts was set up within the framework of the EORTC Receptor and Biomarker Study Group (RBSG). Polyclonal antibodies against VEGF165 were raised in chickens and rabbits, and used in a previously described assay format. The assay was validated and characterized for use in serum, plasma and tumor tissue extracts. The resulting VEGF ELISA was found to be specific for VEGF165 and VEGF121, the main isoforms of VEGF. The assay showed good precision and parallelism in serial dilutions of samples. The assay was not susceptible to interference by heterophilic antibodies because avian antibodies (duck anti-chicken and chicken anti-VEGF) were used in the pre-analyte stage and mammalian antibodies (rabbit anti-VEGF and goat anti-rabbit) in the post-analyte stage. In conclusion, a sensitive, robust and specific VEGF ELISA has been developed. Research into the prognostic value of VEGF employing this assay is currently underway.

Use of heterologous immunoassays for quantification of serum proteins: The case of canine C-reactive protein

The use of heterologous immunoassays containing antibodies raised against a different biological species for quantification of serum proteins is studied and discussed, taking as example the case of the use of a commercially available heterologous assay containing antibodies against human C-reactive protein (hCRP) for quantification of CRP in serum of dogs. This assay was adapted and validated for measurements of canine CRP (cCRP) and compared with three different homologous assays containing species-specific canine antibodies, which are currently commercially available for cCRP determination. Serum samples from healthy and diseased dogs (n = 44) were used. Analytical evaluation included precision, accuracy, limit of detection and lower limit of quantification for all assays. In the case of the heterologous assay also cross-reactivity of the antibody of the heterologous assay with cCRP was evaluated by a Western-Blot analysis giving a positive result. The heterologous assay showed similar results than the homologous assays in all the tests of the analytical evaluation that indicated that the assay was precise and accurate. Method comparison showed a high correlation between all assays (r≥0.9). The Bland-Altman test revealed that the heterologous assay showed a proportional error when compared with the homologous automated assays and a random error when compared with the point-of-care assay. All four CRP assays were able to detect higher CRP values in dogs with inflammatory conditions compared with healthy dogs. It is concluded that heterologous immunoassays could be used for quantification of serum proteins in different species, provided that the antibody has cross-reactivity with the protein to be measured and the assay give satisfactory results in the analytical validation tests. In addition, use of species-specific calibrators and an appropriate batch validation are recommended in these cases.

Divergence of the response induced by xenogenic immunization in the sepsis survival of rats

We have previously described that boosted natural xenoantibodies in rats cross-react to bacteria by targeting carbohydrate antigens. This type of immunization is associated with reduced survival after cecal ligation and puncture (CLP). In the present study, we investigated further this phenomenon by immunizing Lewis rats with three intraperitoneal injections, every other day, of hamster blood compared to saline-injected control animals. One day after the last injection, CLP was performed to produce a low-grade sepsis. Induction of xenoantibodies was associated with a reduction in animal survival after CLP relative to controls (45% vs. 90%, p<0.01). No bacterial blood load was observed after CLP in this model either with or without xenoantibody enhancement, indicating that the augmented mortality was not mediated by a direct effect of boosted xenoantibodies over blood bacteria. Nevertheless, the xenoimmunization produced a systemic inflammatory response in all rats. Additionally, a lack of weight gain at the time of CLP was present in animals that died after the procedure, which was not observed in surviving rats and controls. The cytokine profile at the time of CLP in animals that died after the procedure was characterized by an increase in the serum level of several cytokines, particularly adipokines. In contrast, the cytokine profile at CLP of xenoimmunized rats that survived the procedure was characterized by a reduction in the level of cytokines. In conclusion, this study failed to show a direct effect of boosted xenoantibodies over blood bacterial isolates as cause for the decreased survival after CLP. However, it evidenced that non-infectious systemic inflammation may lead to a pattern of augmented cytokines, particularly adipokines, which impairs survival after subsequent CLP. Therefore, the profile of cytokines existing before the infectious insult appears more crucial than that resulting from the condition for the outcome of sepsis.

Decrease in plasma levels of α-synuclein is evident in patients with Parkinson's disease after elimination of heterophilic antibody interference

There is substantial biochemical, pathological, and genetic evidence that α-synuclein (A-syn) is a principal molecule in the pathogenesis of Parkinson disease (PD). We previously reported that total A-syn levels in cerebrospinal fluid (CSF), measured with the specific enzyme-linked immunosorbent assay (ELISA) developed by ourselves, were decreased in patients with PD, and suggested the usefulness of A-syn in CSF and plasma as a biomarker for the diagnosis of PD. After our report, a considerable number of studies have investigated the levels A-syn in CSF and in blood, but have reported inconclusive results. Such discrepancies have often been attributed not only to the use of different antibodies in the ELISAs but also to interference from hemolysis. In this study we measured the levels of A-syn in CSF and plasma by using our own sandwich ELISA with or without heterophilic antibody (HA) inhibitor in 30 patients with PD and 58 age-matched controls. We thereby revealed that HA interfered with ELISA measurements of A-syn and are accordingly considered to be an important confounder in A-syn ELISAs. HA produced falsely exaggerated signals in A-syn ELISAs more prominently in plasma samples than in CSF samples. After elimination of HA interference, it was found that hemolysis did not have a significant effect on the signals obtained using our A-syn ELISA. Furthermore, plasma levels of A-syn were significantly lower in the PD group compared with the control group following elimination of HA interference with an HA inhibitor. Our results demonstrate that HA was a major confounder that should be controlled in A-syn ELISAs, and that plasma A-syn could be a useful biomarker for the diagnosis of PD if adequately quantified following elimination of HA interference.

Production and evaluation of chicken antibodies against a synthetic peptide from glial growth factor

Neuregulins (NRG) are proteins that belong to the family of epidermal growth factors. It is well established that these factors are essential for the development and maintenance of the nervous system. Due to the difficulty of purifying enough quantities of these factors and the lack of specificity from commercially available antibodies, the aim of this work was to produce antibodies against a synthetic peptide capable to detect and identify neuregulin GGFbeta isoforms. To accomplish this goal, polyclonal antibodies were raised in hens against a synthetic peptide designed from the GGFbeta1 extracellular sequence. The sequence analysis was made using different epitope-predicting programs. Our results showed that the peptide sequence selected was immunogenic because it was capable of inducing a specific type B immune response in the experimental animal model. These antibodies were also capable of recognizing a recombinant GGF protein and GGF isoforms present in different samples. Our results suggest that the development of immunoglobulin Y (IgY) using synthetic peptides represents, a valuable tool for neuroscience research.

Anti-alpha-Gal antibody response following xenogeneic heart valve implantation in adults

BACKGROUND AND AIM OF THE STUDY

The study aim was to investigate the xenoreactive immune response directed at Galalpha1, 3-Galbeta1-4GlcNAc-R (alpha-Gal) which is known to be a major barrier in xenotransplantation, and to identify factors such as age, gender, ABO group and type of implanted tissue that might affect the anti-alpha-Gal immune response in adults subjected to bioprosthetic heart valve (BHV) implantation.

METHODS

A total of 103 early survivors aged > 20 years who underwent cardiac surgery using cardiopulmonary bypass was enrolled. Among the patients (45 males, 58 females; mean age 62.8 years), 66 who underwent BHV implantation were assigned as a study group, while the remainder were assigned to a control group. Serum samples were obtained from all patients on three occasions: before surgery (TO); on postoperative day 1 (T1); and on postoperative day 14 or at discharge (T2). A serum sample was also obtained from 31 patients in the study group at the out-patient clinic (T3) at a mean of 38 days after surgery.

RESULTS

Anti-alpha-Gal antibody reactivity at TO was higher in patients aged < 65 years. Anti-alpha-Gal IgM and IgG reactivity at T2 was higher in the study group when compared to that in controls. In the study group, anti-alpha-Gal IgM and IgG reactivities were decreased at T1, but then increased at T2 when compared to that at TO. Anti-alpha-Gal IgG reactivity remained elevated at T3, but the IgM reactivity declined in the study group. None of the factors, including age, gender, ABO group and type of implanted tissue, had any effect on the anti-alpha-Gal immune response after BHV implantation.

CONCLUSION

BHV implantation in adults elicits an increased formation of anti-alpha-Gal antibodies, with different patterns for each isotype. Based on the study results, host factors including age, gender and blood type might be less important in the anti-alpha-Gal immune response following BHV implantation in adults.

Prevalence of human anti-mouse antibodies (HAMAs) in routine examinations

BACKGROUND

Circulating heterophilic antibodies interfere with immunological assays in laboratory examinations; however, their rate of incidence is currently questionable. We developed an enzyme-linked immunosorbent assay (ELISA) to detect human anti-mouse antibodies (HAMAs) in routine examinations.

METHODS

The study samples were comprised of serum samples obtained from 290 inpatients and outpatients at our hospital. Mouse immunoglobulin G1 (mIgG1), mIgG2a, and mIgG2b were used as the antigens and horseradish peroxidase (HRP)-conjugated anti-human IgG and IgM were used to identify the HAMA isotype.

RESULTS

HAMAs were detected in 11.7% (34/290) of the samples. We observed 18 and 20 samples positive for IgG- and IgM-type HAMAs, respectively. Four samples contained both IgG- and IgM-type HAMAs. HAMAs against mIgG1, mIgG2a, and mIgG2b were found in 21, 14, and 13 samples, respectively. Existence of HAMAs was confirmed by western blotting using mIgG's as the antigens and HAMAs as the primary antibodies. Heterophilic blocking reagent (HBR) was also used to block the heterophilic interactions. Unexpectedly, a low HBR concentration rather enhanced the interactions instead of blocking them.

CONCLUSIONS

A considerable number of HAMA-positive samples, reacting with the heavy chain of mIg, were found in routine examinations. A sufficient amount of HBR should be used for blocking the heterophilic interactions.

Antibody-mediated xenograft injury: mechanisms and protective strategies

The use of porcine organs for clinical transplantation is a promising potential solution to the shortage of human organs. Preformed anti-pig antibody is the primary cause of hyperacute rejection, while elicited antibody can contribute to subsequent "delayed" xenograft rejection. This article will review recent progress to overcome antibody mediated xenograft rejection, through modification of the host immunity and use of genetically engineered pig organs.

Interference by heterophilic antibodies in immunoassays: wrong increase of myoglobin values

Aim of this work is to illustrate how analytical interference in immunoassay may produce serious errors in clinical laboratory results. The sophisticated quality assurance schemes used in many laboratories do not identify erroneous results arising from aberrant samples. Recently attention has been focused on the incidence and implication of false-positive results arising from the presence of certain substances in a patient's serum that interfere with one or more steps in immunoassays. In this paper, we present the case of a 92 year-old woman whose plasma myoglobin concentrations falsely increased when measured using the Beckman Access assay. We demonstrated that heterophilic antibodies accounted for the falsely increased myoglobin values, and we suggest how to resolve such situations.

Mechanism of humoral and cellular immune modulation provided by porcine sertoli cells

The understanding of main mechanisms that determine the ability of immune privilege related to Sertoli cells (SCs) will provide clues for promoting a local tolerogenic environment. In this study, we evaluated the property of humoral and cellular immune response modulation provided by porcine SCs. Porcine SCs were resistant to human antibody and complement-mediated formation of the membrane attack complex (38.41+/-2.77% vs. 55.02+/-5.44%, p=0.027) and cell lysis (42.95+/-1.75% vs. 87.99 +/-2.25%, p<0.001) compared to immortalized aortic endothelial cells, suggesting that porcine SCs are able to escape cellular lysis associated with complement activation by producing one or more immunoprotective factors that may be capable of inhibiting membrane attack complex formation. On the other hand, porcine SCs and their culture supernatant suppressed the up-regulation of CD40 expression (p<0.05) on DCs in the presence of LPS stimulation. These novel findings, as we know, suggest that immune modulatory effects of porcine SCs in the presence of other antigen can be obtained from the first step of antigen presentation. These might open optimistic perspectives for the use of porcine SCs in tolerance induction eliminating the need for chronic immunosuppressive drugs.

Eliminating heterophilic antibody interference for ferritin detection using Olympus F(ab')2 based reagent

Interferences with the Olympus immunoturbidimetric assay for ferritin have been reported because the antibodies used in the immunoassay are derived from rabbits. Rabbits are familiar pets known to be a risk factor for developing heterophilic (or interfering) antibodies. This report shows how the current Olympus Ferritin assay has been improved to eliminate the interference from heterophilic antibodies.

Rapidly induced, T-cell–independent xenoantibody production is mediated by marginal zone B cells and requires help from NK cells

Xenoantibody production directed at a wide variety of T lymphocyte–dependent and T lymphocyte–independent xenoantigens remains the major immunologic obstacle for successful xenotransplantation. The B lymphocyte subpopulations and their helper factors, involved in T-cell–independent xenoantibody production are only partially understood, and their identification will contribute to the clinical applicability of xenotransplantation. Here we show, using models involving T-cell–deficient athymic recipient mice, that rapidly induced, T-cell–independent xenoantibody production is mediated by marginal zone B lymphocytes and requires help from natural killer (NK) cells. This collaboration neither required NK-cell–mediated IFN-γ production, nor NK-cell–mediated cytolytic killing of xenogeneic target cells. The T-cell–independent IgM xenoantibody response could be partially suppressed by CD40L blockade.